Comparison of transmitting boundaries in dynamic finite element analyses using explicit time integration. Short communication

1986 ◽  
Vol 23 (6) ◽  
pp. 229
Keyword(s):  
Finite Element ◽  
Short Communication ◽  
Time Integration ◽  
Finite Element Analyses ◽  
Explicit Time Integration ◽  
Dynamic Finite Element ◽  
Transmitting Boundaries

Design of Extended Pile Shafts for the Effects of Liquefaction

2014 ◽  
Vol 30 (4) ◽  
pp. 1775-1799 ◽  
Author(s):  
Arash Khosravifar ◽  
Ross W. Boulanger ◽  
Sashi K. Kunnath
Keyword(s):  
Finite Element ◽  
Static Analysis ◽  
Ground Motion ◽  
Nonlinear Dynamic ◽  
Soil Structure ◽  
Lateral Spreading ◽  
Earthquake Loading ◽  
Finite Element Analyses ◽  
Dynamic Finite Element ◽  
Parametric Analyses

An equivalent static analysis (ESA) procedure is proposed for the design of extended pile shafts subjected to liquefaction-induced lateral spreading during earthquake loading. The responses of extended pile shafts for a range of soil, structure and ground motion conditions were examined parametrically using nonlinear dynamic finite element analyses (NDA). The results of those parametric analyses were used to develop and calibrate the proposed ESA procedure. The ESA procedure addresses both the nonliquefaction and liquefaction cases, and includes criteria that identify conditions which tend to produce excessive demands or collapse conditions. The ESA procedure, its limitations, and issues important for design are discussed.

Modeling Spatial Rigid Multibody Systems Using an Explicit-Time Integration Finite Element Solver and a Penalty Formulation

2004 ◽  
Author(s):  
Tamer Wasfy
Keyword(s):  
Finite Element ◽  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Time Integration ◽  
Rigid Bodies ◽  
Rotation Matrix ◽  
Explicit Time Integration ◽  
Penalty Formulation ◽  
A New Technique ◽  
Rigid Multibody

A new technique for modeling rigid bodies undergoing spatial motion using an explicit time-integration finite element code is presented. The key elements of the technique are: (a) use of the total rotation matrix relative to the inertial frame to measure the rotation of the rigid bodies; (b) time-integration of the rotational equations of motion in a body fixed (material) frame, with the resulting incremental rotations added to the total rotation matrix; (c) penalty formulation for creating connection points (virtual nodes which do not add extra degrees of freedom) on the rigid-body where joints can be placed. The use of the rotation matrix along with incremental rotation updates circumvents the problem of singularities associated with other types of three and four parameter rotation measures. Benchmark rigid multibody dynamics problems are solved to demonstrate the accuracy of the present technique.

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